Detailed technical documentation for the Xbox 360 controller is typically found through community-maintained wikis and specialized modding forums: ConsoleMods Wiki
For repairs or modifications, specific test points on the bottom of the PCB are often used: VCC: TP18 USB Data+: TP17 USB Data-: TP16 GND: TP2
For a complete look at the underlying 2.4 GHz wireless controller architecture, you can directly view the Intec Xbox Wireless Controller Schematics on FCC ID .